An x-ray tomographic (CT: Computer Tomography) apparatus in accordance with prior art is disclosed in Patent Document 1. Taking account of defects and failures of a photodiode array and the like, the x-ray tomographic apparatus of Patent Document 1 constructs a photodetecting unit by integrating a semiconductor substrate having a photodiode array formed thereon with a ceramic substrate, and makes the photodetecting unit detachable from a base for attachment of the x-ray tomographic apparatus. This allows a maintenance operator to remove a failed photodetecting unit from the base for attachment and replace it with a new photodetecting unit.
In Patent Document 1, a semiconductor substrate smaller than the ceramic substrate is joined to the center of the front face of the ceramic substrate, while through holes penetrating through the ceramic substrate from the front face to the rear face are formed on both sides of the semiconductor substrate. The maintenance operator can attach the photodetecting unit to the base for attachment by inserting bolts through the through holes and fastening the bolts into screw holes formed in the base for attachment. In reverse, loosening the bolts fastened to the base for attachment can remove the photodetecting unit from the base for attachment.
Patent Document 1: Japanese Patent Application Laid-Open No. 2002-162472